This is not unique to what you were working in. I have had this error occur while setting up a Product/Service item, banking, as well as when creating a bill. They have done something that has broken code somewhere. You cannot resolve this by clearing the cache or in an incognito window. You need to close the program and open it in another platform (e.g.: Edge, Chrome, FireFox, etc.). This error will happen in all of them at some point. If for some reason it continues, you'll need to restart your computer and pick a different platform. I wish I was kidding.